Teams at Indian call centres rang computer users claiming to be from tech support and told computer users there were problems with their machines which could be fixed. Photograph: Virginia Mayo/AP

Nineteen websites which were used to perpetrate a phone scam offering "computer support" that defrauded people across the English-speaking world have been closed down by police.

In the scam, reported by the Guardian today, teams at Indian call centres rang computer users claiming to be from tech support. The computer users were then told there were problems with their PC, which could be fixed.

After being told to download a programme that handed over remote control of their computer so the caller could install "fixes", the PC users were told of the £185 charge for subscription to "the preventative service". But the "fixed" computers never had any problems, and the value of the service was dubious.

The Metropolitan police e-crime unit acted in April to take such sites down. Among those shut was supportonclick.com, registered to Pecon Software, a firm based in Kolkata. The company has now opened another support website, called onlinepccare.com, which is the subject of numerous online complaints about cold calling, "bullying", and claims that the caller is from Windows PC care.

But the police are unable to effect refunds for people who were scammed by the cold callers, though they do class the crime as "obtaining money by deception" – in other words, fraud. "Those who believe they have been mis-sold a product or service online should report the matter to trading standards, via its website (www.consumerdirect.gov.uk)," said the PCEU in a statement. "If a criminal offence has clearly been perpetrated the matter should be reported to the police."

The Guardian spoke today to Pecon's customer relationship manager, Vikas Gupta. He said the firm employed 400 people, of whom about 200 worked in telesales, cold calling to generate business for remote PC support. He would not say from where they derived the lists of names and insisted that none of the callers would say they were from Windows tech support. However he admitted there had been "a couple of instances" where "people [from Pecon] did try to influence the customer [to believe] that they were … from Microsoft", and there was "some quality-related feedback" from agents.

Pecon set up its remote support scheme in April 2008, saying it had had an "overwhelming response" from customers in the UK, US, Canada and Australia, and used the supportonclick site – now closed by the e-crime unit – for the service.

Gupta denied knowing of supportonclick, though it was running before he says he joined and shut while he worked there. He said that, as part of a prepared script, the call-centre teams would show people details from the Windows Event Viewer, a program that can worry uninitiated PC owners. He said this was just to help people decide whether to take Pecon's services.

Gupta said he was aware of sites and call centres in Kolkata operating a "support" scam. He said some pretended to call on behalf of onlinepccare.com. "I'd say 80% of the sites are using content stolen from us. They've copied spelling errors from us."

Sources close to the Met e-crime unit said there was "clear evidence of criminality" from the sites taken down.